Recently, in many parts of automobiles, mechanical devices have been replaced with electronic devices. In this situation, the importance of automotive integrated circuits (ICs) for automotive applications has gradually increased.
The difficulty in the design of automotive ICs stems from the fact that a required operating temperature range is wider than that of common ICs. Generally, since the characteristics of a complementary metal-oxide semiconductor (CMOS) device vary depending on temperature, it is considerably difficult to design an integrated circuit (IC) that can maintain consistent functionality across a wide operating temperature range.
when the characteristics of an automotive IC are controlled based on temperature via a temperature sensor, it is possible to fabricate an automotive IC that can achieve high performance over a wide operating temperature range.
An example of a technology for controlling the characteristics and geometrical parameters of a semiconductor circuit using a temperature-dependent signal, as described above, is disclosed in Korean Patent No. 10-0871111 entitled “Temperature Compensated Transistor Device and Temperature Compensation Method.”
The technology disclosed in the above Korean patent is intended to provide a transistor device whose core transistor characteristics are not influenced by operating temperature and a use and temperature compensation method in an IC semiconductor circuit for the transistor device.
According to the technology disclosed in the above Korean patent, there is provided an IC in which a temperature sensor generates a temperature-dependent signal and even the geometrical parameters of the transistor are controlled in response to a temperature-dependent signal, with the result that core characteristics exposed to the outside of the transistor are not influenced by temperature.
However, although it is preferred that the temperature sensor used in the above technology provides a signal linearly dependent on temperature in an ideal case, an effort to improve the linearity of the temperature sensor itself is required due to intrinsic temperature-dependent nonlinear components that the temperature sensor itself has.
A commonly widely used temperature sensor generates a temperature-dependent signal based on the base-emitter voltage difference ΔVBE of a bipolar junction transistor (BJT) pair. Meanwhile, nonlinear components attributable to forward Early effect, reverse Early effect, and high-level injection appear in the ΔVBE-based temperature sensor. Although there are conventional technologies that attempt to compensate for forward Early effect and reverse Early effect in order to generate a linearly temperature-dependent signal by compensating for nonlinear components, it is difficult for most of these conventional technologies to obtain an accurately compensated signal unless nonlinear components attributable to Early effect are quantitatively estimated. However, it is very difficult due to the intrinsic nonlinear components of the transistor to quantitatively estimate the nonlinear components attributable to Early effect.
Meanwhile, a circuit in which a differential output stage or a current mirror is connected behind a ΔVBE-based temperature sensor has been researched. An example of such a circuit is disclosed in U.S. Pat. No. 6,784,746 entitled “Circuit and Method for Correcting Thermal Deviations of One or More Output signals from an Amplifier with Early Effect Compensation.”
However, even with the technology disclosed in the above U.S. patent, it is difficult to generate a consistent, linear temperature-dependent signal in a wide operating bias condition that causes high-level injection.